For a long time, most of our conventional cognitions have felt that fish have no hearing, because we can't see from the appearance that fish have the same body structure as humans have ears. But is this really the case?
In fact, fish don't hear worse than humans, because we're used to seeing things around us in terms of what we can recognize, so it's only natural that creatures without ears lack hearing. Our ears evolved to listen to sounds that travel through the air, but don't forget that sound is not the medium of air. Different solids can also transmit sound information at different speeds and in different ways. It is precisely because fish live in the water, and we do not have the ability to hear the sound transmitted from underwater, so to this day, it is still difficult for us to hear the sounds made by most fish, so we think that they do not hear. It was not until the 20th century, when the underwater sound detection technology matured, that we gradually understood that fish can make their own sounds and have their own way of receiving sounds.
Fish make sounds by rapidly contracting muscles and vibrating fish swim bladders, unlike animals on land who make sounds by using air-vibrating membranes. In addition, fish have a variety of interesting ways to make sounds: rubbing teeth or throat teeth, rubbing bones or gill covers, and even expelling bubbles from the anus can make sounds. And these sounds also have different tones and timbres, similar to the grunts, knocks, cheers, hums, etc. we hear, so that some fish are directly named in relation to their sounds, such as tube-mouth fish.
In the mid-1930s, an Austrian biologist, Karl von Frisch, did an interesting experiment. He took a blind perch as an experimental subject, first put the food with a rope near its residence, the keen sense of smell allowed the sea bass to come out to eat, this operation for a few days, he added another action: before each feeding of the fish, he would blow a whistle, after 6 consecutive days, the sea bass heard the whistle, it would swim out on its own. Through this experiment, it was proved that the sea bass could hear the sounds he made.
With later research, sea bass were able to hear sounds because they evolved a unique hearing organ: The Merriam-Webster ossicles. The Wechsleaf microbones are located on either side of the first four vertebrae behind the fish skull, separated from the vertebrae, and connect like a chain to the gas-filled maw and the liquid-filled area around the inner ear. The role of Wechslets is to enhance hearing, as a conductor and amplifier of sound waves, working like human ossicles. There are also about 8,000 species that have evolved such miraculous functions, and the carp we are familiar with, the fat carp (lamp fish and piranha), the electric eel, the knife fish, etc. all have such evolutionary attributes.
Here we insert an interesting practical case, we usually raise more fighting fish, in the training of fighting fish, in fact, the use of similar principles. When the fighting fish sees the male fish of the same kind, it will show a very demonstrative fighting state, which can be stimulated by just giving a mirror. Therefore, when training fighting fish, we will first do a whistling operation similar to the one mentioned in the above experiment, either with a finger to show the fighting fish, or replace it with other items, and then use a mirror to show the fighting fish, and after activating the combat state, give a little food as a reward. Later, when the fighting fish see these familiar things appear, they will know that they are going to enter the fighting state, and then there will be something to eat. Interested friends may wish to try.
Most of the fish receive sound waves in the range of 50 to 3000 hertz, in the range of 50 to 20,000 hertz for humans, but there are also some fish hearing range can reach 180,000 hertz, far higher than the upper limit of humans, belongs to the category of ultrasound, some studies pointed out that in order to better hear dolphins emit ultrasound, and can better avoid predators evolved.
There are also some fish that can hear very low infrasound waves, such as flounder, perch. However, there is no specific study to show why they can evolve such capabilities, but it is certain that it is inseparable from their native water environment. It can only be speculated that it may be due to ocean currents or climate change, and some forces combine to produce some infrasound environment, and these fish need to use this information to complete migration and other purposes. So for these fish that are very sensitive to hearing, when some of our human activities produce a huge sound, such as the air gun used in offshore oil extraction, it will affect them very much.
Friends who like to fish should know that if they can contact objects in the water on the shore, the sound it makes will affect the surrounding fish, so that basically no fish will be hooked. Especially in the sea fishing on the boat, it is necessary to maintain a quiet environment to increase the probability of the fish being hooked.
Finally, let me share an interesting experiment that is relatively close to our lives: goldfish will do everything possible to make noise in order to eat to attract the attention of their owners. It is said that it is an experiment, in fact, in the daily life of raising ornamental fish, it is often encountered, as long as you carefully observe it, you can find it. If there is a tank of goldfish at home, we feed them at a fixed time every day, and after a few days, when that time comes, the goldfish will be waiting in that place to eat.
If one day you delay the feeding time because you are busy with other things, then the goldfish will also find ways to make a sound to attract your attention. The most common is to stick your mouth out to the surface of the water, then open and close the sound to make a sound to make you pay attention, if it is not enough attention, then you will use your tail to repeatedly slap the surface of the water to make a sound to attract your attention. When you approach the fish tank and feed them something to eat, they will not behave like this. Isn't that interesting? Similarly, some fish that look smarter, such as doghead fish, will have similar vocal behaviors to attract the attention of their owners, such as flicking the wall of a glass fish tank with their tails, or biting a stone with their mouths to knock.
There are actually many interesting things waiting for us to discover about the hearing of fish, such as fish being able to distinguish the direction of sound sources better than humans, and so on.
If you also like to raise ornamental fish, you may wish to start pointing out a point of attention, all you need to know about fish farming is here.